Design: "PBMC from peripheral blood were collected from five pairs of adult MZ twins (10 total samples). The donors were all nominally healthy at sample collection, and their ages ranged from 22-27 years. The cells were first analyzed via FACS, sorted and stored at -80°C. Naïve B cells were defined by expression of CD20 and the absence of CD27. Memory B cells were defined by expression of CD20 and CD27. Naïve CD4+ T cells were defined by expression of CD4, absence of CD8 and absence of CD45RO. Naïve CD8+ T cells were defined by expression of CD8 and absence of CD4 and CD45RO. Central memory T cells were differentiate from naïve cells by expression of CD45RO and CCR7. RNA was purified from each sorted sample, and was reverse transcribed with self designed oligos. Obtained ss cDNA was purified, and the first amplification of the total transcriptome was obtained with self-designed oligos in order to add the Illumina Nextera MID P5 Adapter sequences. Enrichment for the receptor specific sequences was performed, and the Nextera P7 MID sequence was added in the final PCR."

The adaptive immune system’s capability to protect the body requires a highly diverse lymphocyte antigen receptor repertoire. However, the influence of individual genetic and epigenetic differences on these repertoires is not typically measured. By leveraging the unique characteristics of B, CD4+ T, and CD8+ T lymphocyte subsets isolated from monozygotic twins, we have quantified the impact of heritable factors on both the V(D)J recombination process and thymic selection in the case of T cell receptors, and show that the repertoires of both naïve and antigen experienced cells are subject to biases resulting from differences in recombination. We show that biases in V(D)J usage, as well as biased N/P additions, contribute to significant variation in the CDR3 region. Moreover, we show that the relative usage of V and J gene segments is chromosomally biased, with approximately 1.5 times as many rearrangements originating from a single chromosome. These data refine our understanding of the heritable mechanisms affecting the repertoire, and show that biases are evident on a chromosome-wide level.